Valuable tidal meadows
Keystone species
In the 1960’s, Robert T. Paine began to visit Tatoosh Island, where he and his students pried starfish and other animals off the rocks and threw them like frisbees into the ocean. Would removal of one single species cause greater effects than others?
On the shores of the island, there were relatively few plants (mostly algae) and animals (starfish, barnacles, mussels, limpets, anemones) that could cling to the rock during the frequent storms. Removal of the starfish had the biggest effects of all: first the barnacles would thrive, and then the area turned into a vast expanse of mussels. The field of ecology gained a new concept: the keystone species. In addition to the Tatoosh Island starfish, now sea otters, wolves, and in some cases, plants such as eelgrass, are recognized as keystone species in different ecosystems. They share one important characteristic: if the members of a keystone species are removed from an ecological community, the entire web of interrelated organisms collapses.
Nurseries for marine life babies
Out beyond the mudflats are the eelgrass beds that serve as nurseries for Dungeness crab and herring and juvenile salmon and steelhead. Leopard shark young also like to hang out in eelgrass.
Brilliant green sea slugs eat algae off the eelgrass leaves. Without this cleaning, the algae would block light to the eelgrass leaves and the eelgrass would die. Eelgrass is highly valued, not only for its nursery role, but also because it sequesters carbon very efficiently, so it helps to counter climate change.
Eelgrass…was declared “essential habitat” many years ago.
Eelgrass is a flowering plant that grows in a limited band along the shoreline. It can’t grow in water that is too shallow because its leaves need the water to support them. Plus the tide goes out twice a day, and eelgrass needs to stay damp to survive. However, if the water is too deep or too cloudy, eelgrass can’t get enough light for photosynthesis. Eelgrass is so important for the healthy growth and protection of juvenile animals like fishes and Dungeness crab that it was declared “essential habitat” many years ago.
A source for restoration
The eelgrass at Point Molate is very healthy and is often used as a donor to re-establish eelgrass beds that have been damaged. However, the process of re-establishment or planting an eelgrass bed in a new location is tricky and often fails. The reasons for the failure are not well understood (Ward and Beheshti, 2023). Eelgrass is costly to restore, so ensuring the health of existing eelgrass beds is especially important (Bayraktarov et al., 2015).
Photos Credits: Jack Scheinman
Tidal meadows references:
https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.4642
https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/15-1077
Keystone species references:
http://daily.jstor.org/how-the-keystone-species-concept-transformed-ecology/